Crane with telescope jib

ABSTRACT

A crane includes a telescopic jib having telescopic jib sections and a base jib. The telescopic sections are arranged so that they can be axially moved into and out of the base jib individually. Locking pins are used hold the telescopic sections in place once they are in the required position. A hydraulic piston-cylinder unit arranged in the telescopic jib can push or pull individual jib sections when the respective locking bolts are removed. The movable portion of the piston-cylinder unit has two securing and locking units located at opposing ends of the movable portion. To move the jib section, one of the securing and locking units is connected to the jib section to be moved and the movement of the movable portions pushed or pulls the telescopic section. Once the jib section is moved to a desired position, the locking pin is reinserted to hold the position of the jib section. Since there are two securing and locking units, the piston-cylinder unit is approximately half the length of the telescopic section.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention is directed to a crane with a telescope jib having aplurality of telescoping sections which are individually moved into andout of a base jib.

2. Description of the Prior Art

In a prior art crane with telescope jib known from EP 0 661 234 A1,individual telescoping sections which can telescope out are moved outand in only by a single-stage piston-cylinder unit after locking pinconnections are released, and are bolted in the respective moved out ormoved in positions by locking bolts which are spring-loaded in thedirection of their locked positions. A piston rod of the single-stagepiston-cylinder unit is articulated at the jib articulation point whichterminates the inner end of the outer section. A driver device which canbe coupled with receptacles of the telescoping sections is arranged inthe area of the end of the cylinder from which the piston rod emerges.The driver device comprises a hydraulic block with cylinders located onopposing sides of the hydraulic block. Bolts are formed by pistons ofthe cylinders and can be moved in and out, of the cylinders. A hydraulicpiston-cylinder unit is arranged perpendicular to the locking bolts foractuating the respective locking bolt. The hydraulic elements of thedriver device are in an operative connection such that the radiallylocated piston-cylinder unit for pulling in the respective locking boltcan be actuated only when the driver device is coupled, via the lockingbolts, with the section which is to be telescoped out or in.

A comparable prior art telescoping system is known from EP 0 754 646 A1.This telescoping system has a base section and at least two sectionswhich can telescope relative to the base section. The sections are fixedin their respective position relative to one another by removableinsertion bolts (locking bolts) penetrating the walls of adjoiningsections. The telescoping system further has a, preferably single-stage,lift cylinder which is limited by the sections and which is acted uponat both sides by pressure medium. This lift cylinder is provided withdrivers which can be brought into an operative engagement with therespective section to be displaced. As is the case in the prior artmentioned above, the piston rod of the piston-cylinder unit isarticulated at the inner end of the outer section. Both knownsuggestions have the disadvantage that the oil supply to thepiston-cylinder unit is carried out on the inside and long distances andwith the formation of a corresponding turbulence for returning the oilsupply to the oil supply storage tank. This reduces the telescopingspeed. Further, the weight of the main jib head is increased by thequantity of oil located in the piston-cylinder unit, which reduces theuseable load.

Another prior art crane is disclosed in DE 31 25 603 A1 including atelescope jib with a base jib and three telescoping sections which canbe moved in and out directly or indirectly via chain drives by means ofa single-stage piston-cylinder unit. The cylinder housing of thepiston-cylinder unit is articulated by its rear end at the inner end ofthe base jib. The piston rod is connected at the front end, via a bolt,with a cylinder box which encloses the moved out piston rod and which isconnected in the vicinity of its inner end by a bolt with the side wallsof the first telescoping section. This construction is disadvantageousin that all three telescoping sections can only be moved in and outjointly and it is not possible to purposely move only one telescopingsection in and out of the base jib.

SUMMARY OF THE INVENTION

It is the object of the invention to provide a crane with a telescopicjib which can be produced economically while retaining the principle ofthe individual telescoping capability of the sections by means of apiston-cylinder unit and which enables an increased telescoping speedcompared with the known prior art and whose useable load is greater.

The object of the invention is met by a crane with a telescopic jib, thetelescopic jib comprising a base jib having an inner end and an outerend, first and second jib sections arranged in the base jib and axiallymovable therein between moved-in and moved-out positions, apiston-cylinder unit having a cylinder housing and a piston rod having afree end articulated at the inner and of the base jib, a first securingand locking unit arranged at an inner end of the cylinder housing and asecond securing and locking unit arranged at an outer end of thecylinder housing, the first and second locking units having securingbolts selectively connecting to one of the first and second jibsections, and locking bolts arrangeable in recesses of the first andsecond jib sections for holding the first and second jib sections in themoved-in or moved-out position.

The object of the invention is also met by a crane with a telescopicjib, the telescopic jib comprising a base jib having an inner end and anouter end, first and second jib sections arranged in the base jib andaxially movable therein between moved-in and moved-out positions, apiston-cylinder unit having a cylinder housing and a piston rod, thecylinder housing having a front end and a rear end articulated at theinner end of said base jib, a guiding and pulling device connected at afront end of the piston rod and extending parallel to thepiston-cylinder unit, a first securing and locking unit arranged at afront end of the guiding and pulling device and a second securing andlocking unit arranged at a rear end of the guiding and pulling device,the first and second locking units having securing bolts selectivelyconnecting to one of the first and second jib sections, and lockingbolts arrangeable in recesses of the first and second jib sections forholding the first and second jib sections in the moved-in or moved-outposition.

In contrast to the known prior art, a securing and locking unit that canbe coupled with recesses in the sections which can telescope out isfastened respectively to the inner and outer end of a displaceableelement of a piston-cylinder unit. Optionally, the displaceable elementof the piston-cylinder unit may be the cylinder housing, in which casethe piston rod is articulated by its rear end at the inner end of thebase jib, or the displaceable element of the piston-cylinder unit can bethe piston rod, in which case the cylinder housing is articulated by itsrear end at the inner end of the base jib. In either case, it isadvantageous that the length of the piston-cylinder unit amounts to onlyabout 50% of the length of the main jib due to the arrangement of twosecuring and locking units. A shorter piston-cylinder unit means ashorter bending length, so that the piston-cylinder unit may be designedmore favorably with respect to dimensioning while retaining the samelifting force. This, in turn, has a direct effect on the weight which,despite the added weight due to the arrangement of a second securing andlocking unit, is lower in comparison to a piston-cylinder unit whichextends 100-% of the length of the main jib. Two lift procedures arerequired for fully telescoping each individual telescoping section. Theembodiment with a cylinder housing articulated at the base jib ispreferably selected, wherein the piston rod is connected with a guidingand pulling device oriented parallel to the piston-cylinder unit. Twosecuring and locking units are fastened to the inner and outer end ofthe guiding and pulling device. The guiding and pulling device has acrosspiece fastened to the front end of the piston rod and two guideelements located, respectively, to the right and left of the cylinderhousing. The front end of the guide element is connected with thecrosspiece on one side and the front end area of the guide element isconnected with the second securing and locking unit on the other sideand the rear ends are connected with the first securing and lockingunit. The crosspiece preferably has a flat section or profile which isstiffened by a web plate and the guide elements comprise box sections orprofiles with internal plate reinforcements.

The securing and locking unit arranged at the inner end has a bushingwhich is displaceable on the cylinder housing of the piston-cylinderunit and which is connected with the two guide elements. A sliding piecewhich is in an operative connection mechanically with the two securingbolts and the gripper by means of guide grooves and guide rings isarranged on this bushing so as to be displaceable. The arrangement ofguide grooves and guide rings is selected in such a way that therespective locking bolt can be pulled only when the two securing boltsare moved into the respective lateral recesses of the telescopingsections and, conversely, it is only possible for the two securing boltsto move out of the respective recesses when the respective locking boltis set. The actuating element for the sliding piece is preferably apiston-cylinder unit connected with the guide elements. Thispiston-cylinder unit is arranged so as to be oriented parallel to thecylinder housing of the piston-cylinder unit moving the sections. In thesecuring and locking unit arranged at the outer end, the arrangement ofa bushing may be omitted. The rest of the elements are coincident. Forthe purpose of setting the locking bolts, the sections also haverecesses in the central area in addition to the recesses provided at theinner and outer end. These additional recesses are preferably arrangedone above the other at approximately 50% of the length of the sections.This means that the locking is carried out by means of the securing andlocking unit arranged at the inner end for sliding in and out toapproximately 50% of the length and locking is carried out by means ofthe securing and locking unit arranged at the outer end for sliding inand out further between 50 and 100%.

The preferred construction for the telescoping capability of thesections using a known piston-cylinder unit has the advantage that itcan be produced economically and has good guiding with respect to thesecuring and locking unit. Moreover, the oil supply to thepiston-cylinder unit is facilitated in that the oil feed at the baseside can be realized directly at the end of the base jib with thecylinder housing. The oil quantity located in the cylinder housing canaccordingly be returned by hydraulic connections having a large nominalwidth to the hydraulic tank along the shortest path without turbulence,which is required for increasing speed during the telescoping process.The center-of-gravity position of the moved out main jib is shiftedtoward the base point of the main jib by the inherent weight of thehydraulic oil of the cylinder, which means a reduction of the weight ofthe main jib head and, therefore, an increase in load. The mechanicallocking which cannot be influenced by electric or hydraulic interferenceis also advantageous.

BRIEF DESCRIPTION OF THE DRAWING

In the drawings wherein like reference characters denote similarelements throughout the several views:

FIG. 1a is a side view of a rear end of a telescopic jib according to anembodiment of the invention in the moved-in position;

FIG. 1b is a side view of a front end of the telescopic jib of FIG. 1a;

FIG. 2a is a more detailed of area X in FIG. 1a;

FIG. 2b is a top view of the detailed area shown in FIG. 2a;

FIG. 3 is a perspective view of a first securing and locking unitaccording to the present invention;

FIGS. 4a-4 d show stages for moving out one jib section of thetelescopic jib of FIG. 1a;

FIG. 5 is a sectional view of the telescopic jib of FIG. 4b along lineV—V with the securing elements in a locked position;

FIG. 6 is a sectional view similar to FIG. 5 with the securing elementsin the unlocked position.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

According to FIGS. 1a, 1 b and 2 a, 2 b, a plurality of telescopingsections 2-5 are mounted so as to be axially displaceable one inside theother in a base jib 1 having an oval cross section. A constructionalunit of this type may be used as a telescope jib for stationary ormobile cranes. The telescoping capability of the individual telescopingsections 2 to 5 is effected in this embodiment example by a single-stagepiston-cylinder unit, having a cylinder housing 6 and a piston rod 16.In contrast to conventional constructions, the cylinder housing 6,rather than the piston rod 16 (FIG. 2b), is articulated by a bearing 7at a jib articulation piece 18 terminating the base jib 1. In the firstto fourth telescoping sections 2 to 5, respective locking bolts 2A to 5Aare provided in the area of the rear bearing. The telescoping sections2-5 are connected with one another by these locking bolts 2A to 5A.Further, each telescoping section 2 to has a recess 2B-5B on a firstside and a recess 2B′-5B′ on a second side, respectively. A firstsecuring and locking unit 8.1 includes first and second securing bolts13-13′ insertable into recesses 2B-5B and 2B′-5B′, respectively. Guideelements 9, 9′, each having a front end and a back end are arranged onopposing sides of the cylinder housing 6. A crosspiece 11 which isstiffened by a web plate 30 is connected to the front ends of the guideelements 9, 9′. A support roller 12 is arranged in the area of thecrosspiece 11 for support. Head rollers 15, 15′ are provided at the headpiece 19 of the base jib 1 for the rope guide, not shown in more detail.According to the invention, a second securing and locking unit 8.2 isarranged at the piston-cylinder unit at the outer end, wherein, in thiscase, the piston-cylinder unit is single-stage. The second securing andlocking unit 8.2 coincides with the first securing and locking unit 8.1arranged at the inner end. A drive 14 faces the inner end of thetelescope jib. The hydraulic supply of the drive 14 of the first andsecond securing and locking units 8.1, 8.2 is carried out by first andsecond control and bubble storage units 35.1, 35.2. Depending on thelength of the piston-cylinder unit moving the sections 2 to 5, the twocontrol and bubble storage units 35.1, 35.2 may be combined to form ablock. A guide construction 10 is arranged for the energy supply 17 ofthe respective first and second securing and locking units 8.1, 8.2 atthe underside of the piston-cylinder unit.

FIG. 3 shows a perspective view of the details of the first securing andlocking unit 8.1 arranged at the inner end. It comprises a bushing 28which is arranged on the cylinder housing 6 of the piston-cylinder unitso as to be axially displaceable theron and which is connected with theend regions of the guide elements 9, 9′. The connection of guideelements 9, 9′ to the bushing 28 is carried out by means of bolts 26.1,26.2 to 26.1″, 26.2″ (see FIGS. 2a, b). A sliding piece 21 is arrangedon the bushing 28 so as to be displaceable. The displacement of thesliding piece 21 on the busing 28 is carried out by a piston-cylinderunit 14 which is oriented parallel to the cylinder housing 6 and whichis fixedly connected, in turn, with the bushing 28. Web plates 29, 29′lying in the horizontal plane and provided with a guide grooves 27, 27′are respectively arranged to the right and left of the sliding piece 21.The guide grooves 27, 27′ cooperate with guide rings 22, 22′ (see alsoFIGS. 4, 5) which are connected with the respective securing bolts 13,13′. The two securing bolts 13, 13′ located opposite one another aremoveable in and out of the respective lateral recesses 2B-5B, 5B′ and2B′ (see also FIGS. 4, 5). A fork plate 31 with a guide ring 23 isprovided at the sliding piece 21 so as to be oriented perpendicular tothe two web plates 29, 29′. This guide ring 23 cooperates with a guidegroove 33 arranged at a gripper 24. Which is guided in a bushing 32 inaccordance with the views in FIGS. 4, 5. Proximity switches 25, 25.1,25′, 25.1′, 25.2, 25.3, 25.2′, 25.3′ are arranged in pairs in the upperregion of the sliding piece 21. These proximity switches signal approachto one of the lateral recesses 2B, 2B′ to 5B, 5B′ during thedisplacement of first securing and locking unit 8.1 along the cylinderhousing 6.

The individual steps for telescoping are shown in FIGS. 4a-4 d in stepsequences 4 a-4 d. Step sequence FIG. 4a is identical to the view inFIGS. 1a, b, so that a description need not be repeated. For moving out,the piston-cylinder unit is actuated and the piston rod 16, includingthe guide elements 9, 9′, is moved toward the left. In order to move outthe innermost telescoping section 5, the first securing and locking unit8.1 arranged at the inner end is moved along the cylinder housing untilit can be coupled with the corresponding locking bolt 5A. Beforedisengaging the locking of the fourth telescoping section 5 with thethird telescoping section 4, the securing bolts 13, 13′ are pushed intothe lateral recesses 5B, 5B′ provided for this purpose corresponding tothe view in FIG. 4. In this way, the securing and locking unit 8.1 isbolted to the innermost telescoping section 5. According to stepsequence FIG. 4b, the innermost telescoping section 5 is partially slidout by displacing the piston rod 16 toward the left. FIG. 4b shows theend state of this first move-out phase. The locking bolt 5A of theinnermost telescoping section 5 is then pushed into the recess 34.1located approximately in the center of the third telescoping section 4.In this way, the innermost telescoping section 5 which is partiallypushed out is locked with the third telescoping section 4.

FIG. 4c shows the end state of the return movement of the first securingand locking unit 8.1 and the engagement of the locking bolt 5A of thefourth telescoping section 5 by means of the second securing and lockingunit 8.2 arranged, according to the invention, at the outer end of thepiston-cylinder unit. However, before this locking can be disengaged,the securing bolts 13, 13′ are slid into the lateral recesses 5B, 5B′provided for this purpose. In this way, the second securing and lockingunit 8.2 is bolted with the innermost telescoping section 5.

FIG. 4d shows the end state in which the innermost telescoping section 5is completely slid out, after activation of the piston-cylinder unit.For the purpose of locking the fourth telescoping section 5 with thethird telescoping section 4, the locking bolt 5A engages in thecorresponding receptacle of the third telescoping section 4. At the sametime, the two securing bolts 13, 13′ are moved out of the lateralrecesses 5B, 5B′. The movable part of the piston-cylinder unit thenmoves back into the initial position again in a manner comparable toFIG. 4a.

The sliding out of the rest of the telescoping sections 2 to 4 will notbe shown or described so as to save space and avoid repetition of theprocess steps.

FIG. 5 shows a section along the in direction V—V from FIG. 4b. Thisview, shows a situation in which the innermost telescoping section 5 isbolted with the securing and locking unit 8.1 arranged at the inner end.For this purpose, the securing bolts 13, 13′ arranged in the firstsecuring and locking unit 8.1 are moved toward the right and left intothe recesses 5B, 5B′ arranged in the innermost telescoping section 5. Bymeans of this bolting, the innermost telescoping section 5 is bolted tothe piston-cylinder unit via the first securing and locking unit 8.1.The locking bolt 5A is then pulled out of the upper recess 34.1, so thatthe innermost telescoping section 5 can be slid out by moving the pistonrod 16.

FIG. 6 shows the same section V—V in FIG. 4b, with the difference thatthe locking bolt 5A of the innermost telescoping section 5 is pushedinto the upper recess 34.1 of the third telescoping section 4.Consequently, the securing bolts 13, 13′ are moved out of the lateralrecesses 5B, 5B′ by the mechanical coupling described with reference toFIG. 3.

What is claimed is:
 1. A crane with a telescopic jib, said telescopicjib comprising: a base jib having an inner end and an outer end; firstand second jib sections arranged in said base jib and axially movabletherein between moved-in and moved-out positions; a piston-cylinder unithaving a cylinder housing and a piston rod having a free end articulatedat said inner and of said base jib; a first securing and locking unitarranged at an inner end of said cylinder housing and a second securingand locking unit arranged at an outer end of said cylinder housing, saidfirst and second locking units having securing bolts selectivelyconnecting to one of said first and second jib sections; and lockingbolts arrangeable in recesses of said first and second jib sections forholding said first and second jib sections in the moved-in or moved-outposition.
 2. The crane of claim 1, wherein said recesses in said firstand second jib sections comprise a central recess in a central area ofsaid first and second jib sections and inner end and outer end recessesat the inner and outer ends of said first and second jib sections. 3.The crane of claims 2, wherein said central recesses are arranged atapproximately half the length of the first and second jib sections. 4.The crane of claim 1, wherein said first and second securing and lockingunits each comprise a hydraulic block with opposing cylinders for saidsecuring bolts and a locking bolt piston-cylinder unit arrangeperpendicular to said opposing cylinders for actuating said lockingbolts.
 5. The crane according to claim 4, wherein said locking boltpiston-cylinder unit is operatively arrange such that said locking boltsare removable only when said securing bolts are engaged.
 6. A crane witha telescopic jib, said telescopic jib comprising: a base jib having aninner end and an outer end; first and second jib sections arranged insaid base jib and axially movable therein between moved-in and moved-outpositions; a piston-cylinder unit having a cylinder housing and a pistonrod, said cylinder housing having a front end and a rear end articulatedat said inner end of said base jib; a guiding and pulling deviceconnected at a front end of said piston rod and extending parallel tosaid piston-cylinder unit; a first securing and locking unit arranged ata front end of said guiding and pulling device and a second securing andlocking unit arranged at a rear end of said guiding and pulling device,said first and second locking units having securing bolts selectivelyconnecting to one of said first and second jib sections; and lockingbolts arrangeable in recesses of said first and second jib sections forholding said first and second jib sections in the moved-in or moved-outposition.
 7. The crane of claim 6, wherein said recesses in said firstand second jib sections comprise a central recess in a central area ofsaid first and second jib sections and inner end and outer end recessesat the inner and outer ends of said first and second jib sections. 8.The crane of claim 7, wherein said central recesses are arranged atapproximately half the length of the first and second jib sections. 9.The crane of claim 6, wherein said first and second securing and lockingunits each comprise a hydraulic block with opposing cylinders for saidsecuring bolts and a locking bolt piston-cylinder unit arrangeperpendicular to said opposing cylinders for actuating said lockingbolts.
 10. The crane according to claim 9, wherein said locking boltpiston-cylinder unit is operatively arrange such that said locking boltsare removable only when said securing bolts are engaged.
 11. The craneaccording to claim 6, wherein said guiding and pulling device comprisesa crosspiece fastened to said front end of said piston rod and two guideelements located on opposing sides of said cylinder housing, wherein anend of said two guide element connected to said cross piece is connectedto said second securing and locking unit and the opposing ends of saidtwo guide elements are connected to said first securing and lockingunit.
 12. The crane of claim 11, wherein said cross piece has a flatprofile and comprises a stiffener.
 13. The crane of claim 11, whereinsaid two guide element have rectangular cross sections.
 14. The crane ofclaim 13, wherein the inner sides of the guide elements further comprisestiffened plates.
 15. The crane of claim 6, wherein said first securingand locking unit comprises a bushing displaceably arranged on saidcylindrical housing and connected to said two guide elements, andwherein both of said first and second securing and locking unitscomprise a gripper for selectively engaging said locking bolt andsliding pieces connected with an actuating element, said sliding piecebeing in operative connection with said securing bolts and said gripper.16. The crane of claim 15, wherein said sliding piece comprises opposingweb plates comprising guide grooves, guide rings arranged in said guidegrooves and arranged on said first and second securing bolts, saidsliding piece further comprising a fork plate comprising a guide ringand extending perpendicular to said web plates, said guide ring incooperative engagement with a groove in said gripper, and furthercomprising a bushing in which said gripper is guided.
 17. The crane ofclaim 16, wherein said groove in said gripper and said guide grooves insaid web plates are arranged so that said locking bolt is engage whensaid securing bolts are disengaged and said securing bolts are engagedwhen said locking bolt is removed from said recess.
 18. The crane ofclaim 15, wherein said first and second securing and locking units eachcomprise an actuating element for actuating said sliding piece, saidactuating device comprising a piston-cylinder unit.
 19. The crane ofclaim 18, wherein said actuating element of each of said first andsecond securing and locking units is arranged parallel to said cylinderhousing.